Improvement in carriage-springs



r I BIT. HENRY.

- r I Carriage Spring I No. 100,626. Patented March 851870.

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BENJAMIN T. HENRY, oFNnW'nAvEN, CONNECTICUT.

, Letters Patent No. 100,626, dated M arch ,8, 1870,

ElviraOVEIVJEN'I' IN CARRIAGE-SPRINGS.

The Schedule referred to in these Letters Patent and making part of the same Toall iwhom it may concern f Be it known that I, BENJAMIN HE RY, of New Haven, in the county of N ew, Haven, and State of Connecticut, have invented a new Improvement in Oa-rriagesprings; and I do hereby declare the follow- .ing, when taken in connection with the accompanying drawings and the letters of reference marked thereon, to be-a full, clear, and exact description of the same,

and which said drawings constitute part of this specification, and representin- Figure l, a sidewiew of a single spring; and in Figure 2, diagram illustrating the principle of coustruction of this spring.

This'iuvcntion relates to an improvement-in springs for land carriages, commonly formedfiom several layms or plates of steel laid one above the other, and

known as'ellipt-ic springs',the objectbeing to construct a spring from a single plate of metal. \Vhile I am aware that this object has been atteinptedlby rolling the plate from the center toward the ends of a gradual and regular ,diminislnI amLalso aware'that such construction has invariably proved a failure, inasmuch as by practical tests the springs thus constructed are found'to break at about the same place, that is, about midway between the center and end of the spring.

the greatest strain upon the spring is at the center, and the leastatthecnds, it follows that there must be a proportionate thickness, whereby an equal strength may be maintained throughout theentire length of the spring; and 1 I My invention consists. in' constructing 'the spring from a single thickness of metal, rolled from the center toward the end, diminishing in thickness as the strain somewhere from the point f toward the ends of the spring. To avoid this, I construct my spring upon the principle shown in diagram, fig. 2, the same refer,- ence beingused as in fig. 1.

At the point (I it will be evident that the breakingstrain is as nothing, that is to say, a perfect edge or point of metal there would support any amount at the center a-.. a k g By p'racticaljtests I find that the breaking-strain upon the spril'ig; from the point a to the point 11,.diminishes in proportion to the thickness ascertained by describing the upper liue'froin one center a of a given radius, and the undersidefroln another center at of the same radius, and upon this principle .1 construct the spring as shown in fig, 1, as the spring cannotbe a complete half circle, as in fig. 2, the points (1 must be of snfiicient thicknessto supportthe weight at the center, then finding, as in .fig. 2, that at the point f ,the' metal is' about tWo-thirds-the thickness of the metal at the point a, I make the thickness at the point f, the same as at the point (hand two-thirds the difference between the point I and point a, then these I points a (l and f being formed, and the proper curvatnre given to either the upper or lower line, I finda common center to these said points, and describe the circle to intersect the said points, which gives a pro- 1 portionate thickness to the spring throughout its length Thus, commen cing at the center, I draw the metal dow n,

decreasing toward the ends in the proportion described hence I produce a spring which is no more liable to break in one place than another, and the elasticity of which is alike at all points.

I claim, as my invention-- Carriage-springs formed from a single piece or thickness of metal, diminishing in thickness from the center toward each end in propoitiomaml substantially in the manner set forth.

B. T. HENRY.

' Witnesses J H. SHUMWAY,

A. J. 'Iinnrrs. 

